(* queen.pasc *)

(* comprehensive test case, for your fun and 5 more points*)

(* output: 92 chess boards *)

program queen is
var
 col: array(1..8) of 1..8;
 colfree: array(1..8) of integer;
 upfree: array(2..16) of integer;
 downfree: array(-7..7) of integer;
 row: 0..8;
 x: integer;
 num: integer;

 procedure writeboard is
 var
   j, i: 1..8;
   temp: array(1..8) of char;
 begin
   num:= num+1;
   write(num);
   write('\n');
   for i := 1 to 8 loop
     for j := 1 to 8 loop
       if i = col(j) then temp(j) := 'Q' else temp(j) := 'X'
       endif;
     endloop;
     write(temp(1), ' ', temp(2), ' ', temp(3), ' ', temp(4), ' ',
             temp(5), ' ', temp (6), ' ', temp(7), ' ', temp(8));
     write('\n');
   endloop;
   write('\n');
 end;

 procedure addqueen is
 var
   c:1..8;

  begin
   row:= row+1;
   for c := 1 to 8 loop
     if (colfree(c)=1) and (upfree(row+c)=1) and (downfree(row-c)=1) 
     then
       col(row) := c;
       colfree(c) := 0;
       upfree(row+c) := 0;
       downfree(row-c) := 0;
       if row = 8 then writeboard else addqueen endif;
       colfree(c) := 1;
       upfree(row+c) := 1;
       downfree(row-c) := 1
     endif;
   endloop;
   row:= row-1
 end;
  
begin
 num := 0;
 row:=0;
 for x := 1 to 8 loop colfree(x):= 1 endloop;
 for x := 2 to 16 loop  upfree(x):= 1 endloop;
 for x := -7 to 7 loop  downfree(x):= 1 endloop;
 addqueen
end.